Ignition system



Aug. 24, 1948. v. WELGE IGNITION SYSTEM Q 2 Sheets-Sheet 1 QQ Q Filed April- 21, 1945 v. WELGE Aug. 24, 1948.

v IGNITION SYSTEM Filed April 21, 1945 2 sheets-sheet 2 ill U u u 0 I v Patented Aug. 24,

Victor Welge, San Diego, Calif., winner to Consolidated Vultee Aircraft Corporation, ,San Diego, Calif.. a corporation of Delaware Application Apl'll zl, 1945, Serial No. 589,558 18 Claims. ((71- 128-148) The present invention relates in general to electronics and has more particularly reference to the elimination or suppression of radio frequency interference in electronic equipment,

more particularly radio apparatus and more especially interference resulting from operation of ignition systems such as are employed with internal combustion engines.

Conventional spark plug ignition systems, such as are commonly used for the operation of internal combustion engines and other devices requiring ignition, provide a loop circuit from the source of sparking power to the spark gap and back along a ground circuit to the power source. Such a loop circuit forms an effective antenna system capable of radiating electrical disturb ances whenever radio frequency impulses are set up in the ignition system as a result of sparking at the spark plug gap. Such disturbances. because of the resulting effect thereof upon the operation of electronic equipment; particularly radio transmitting and receiving apparatus, are commonly designated as interference.

Another object of theinvention is to provide. an improved ignition system which. for many purposes, need not be shielded for the suppression of interference, the system inherently suppressa ing interference within practical noise level limits.

Another object of the invention is to provide an improved ignition systemrrequiring a minimum of effort to maintain the system in condition such that ignition interference is held at or below a prescribed minimum leveiwhen the system is in operation. r

- Another important object of the invention is to provide an ignition system-for internal combus- 'tlon engines having improved means for the transmission of electrical energy from a power source to thesparking gaps of thesystem, without radiating interference appreciably from the. system. i i

Another object is' to provide an ignition system employing a remote ignition control or cuts-off, ineluding means for suppressing the radiation of radio frequency disturbances initiated in the sys- Heretofore, efforts have been made to minimize the unwanted effects of interference by applying suppressors, in the form of resistance units, in

the high voltage or sparking circuit, of the ignition system, in order 'to reduce current flow in the circuit and hence, to some extent, suppress the effects of radio frequency interference. The use of suppressors, however, in reducing current flow in the sparking circuit impairs sparking efiiciency. Anti-interference shielding has also been applied, without entlrely satisfactory results, in an effort to reduce the radiation of interference causing disturbances from ignition systems.

An important object of the present invention is to provide a novel ignition system for internal combustion engines having features inherently tending to cancel radio frequency impulses in the system, and also to suppress radiation of such impulses as may be established in the system, to thereby minimize interference effects created through the operation of the ignition system.

Another object of the invention is to provide an improved ignition system including simplified shielding means for minimizing radio frequency interference as a'result of the operation of the system; a further object being to provide a system. the operation of which 'willestablish minimum interference noise for a given degree of shielding, and which, for a'given minimum noise level to be maintained, requires appreciably less shielding than is necessary for systems of the character heretofore provided.

tem, including the remote control means, when the same is in operation.

Another object of the invention is to provide a substantially disturbance-free ignition system embodying an ignition circuit having an isolated return path for sparking current flowing in. the system.

Another important object is to provide. im-v proved circuit means for the transmission ,of electrical energy from a power source to the j sparking-gaps ofan ignition system which inherently minimizes the radiation of radio frequency electrical disturbances; a further'obiect being. to incorporate the; several features of. v

novelty in ignition systems embodying a conven tional distributor and either a magneto or an.

ignition coil. 1 r V The foregoing and numerousother important u objects, advantages, and inherent fuhctionslof the invention will become apparent as the invenl tion is more fully understood from the-following description, which, taken in conjunction withuthe accompanying drawings, discloses a preferrecri: embodiment of the invention. Referring to the drawings:- A Fig. 1 comprises a wiring diagram illustrating an ignition system embodying the present inven' -"i r tion and incorporating a power source comprising a battery powered ignition coil; Fig. 2 is a wiring diagram illustrating an alternate ignition system embodying the present 'in-' vention and incorporating a power source com prising a magneto;

names Fig. 3 is a diagram illustrating a modified form of power source which may be employed in the systems'illustrated in Figs. 1 and 2;

Fig. (is a diagram illustrating a modified form of a portion of the ignition system which may be used with a power source of the form shown in any of Figs. 1, 2 or 3: and

Fig. 5 is a diagram illustrating another modiiied form of a portion of the ignition system which may be used with a power source of the form shown in any of Figs. 1, 2 and 3.

To illustrate the invention, the drawings show ignition systems embodying means for suppressing radio frequency disturbances. These ignition systems each comprise one or more spark plugs ii forming sparking gaps, each spark plug being connected by suitable conductor means it with a source of sparking power. Buch source, in each of the illustrated embodiments. comprises the secondary or high voltage coil ll of a sparking voltage generator of suitable character. such as the ignition coil means l'l, shown in Fig. 1 of the drawings, or the magneto means it. shown in Figs. 2 and 3. Each system, where the same serves more than one spark plug II, will include distributormechanism ll interposed in the conductor means it. which interconnects'the high tension source it of sparking power with the spark plugs. The distributor mechanism, 0! course, serves to distribute sparking power to the plugs, tor the purpose of causing the same to'iire or spark at a desired instant of time during the operating cycle of the device It with which the spark plugs are associated.

In order to accomplish the suppression of such radio frequency interference as may develop as a result of the operation oi the ignition systems. the distributor mechanisms II and also the source of sparking power may be, and preferably are, mounted in enclosing housings II and 21 comprising preferably grounded shields for the retention of any electrical disturbances that may be set up as a result of the operation of the distributor mechanism and of the ignition coil means i 'l or the magneto ll.

In order to reduce the production of radio frequency disturbances, the present invention, as shown more particularly in Figs. 1-4, employs balanced two-wire circuits between the source of sparking power and the spark plugs. To this end. the high tension coil II, in each embodiment. is provided with a grounded center tap N, which may be conveniently connected to ground, as by attaching the same to the grounded housing 21. which encloses the coil. The outer ends of the coil ll, thus, at any instant, will be at equal and opposite electrical potential with respect to round.

Where distributor means 2i forms a part of the ignition system, the conductor means It may include a section Ii between each of the spark plugs and th distributor mechanism, and a section It interconnected between the distributor mechanism II and the source ll of sparking power. the coil ends being connected by the conductors 33 to the distributor mechanism Ii, which preferably comprises a distributor having dupliacute. or dual, distributor devices it and 81. Each of these devices comprises a rotary arm and cooperating stationary contacts adapted for successive engagement with the arm as the same rotates. The distributor devices I! and ll-serve to connect the coil-in succession to the several two-wire cable sections ll leading to the spark plugs. The distributor arms and contacts and the cable sections 3i and 83 are insulated from ground and thus form opposite sides of loop circuits extending between the power source and each spark plug. the opposite sides of each loop circuit having substantially identical electrical characteristics at all times.

I As shown in the drawings, the rotating arms of the distributor mechanisms make successive contact each with four stationary contact elements, each of which is connected to a spark plug. The systems illustratedare thus adapted to serve four spark plugs, of which only one is illustrated. The several plugs are, of course, preferably connected with the .distributor mechanism in identical fashion. It will be obvious, however, that any number of spark plugs may be served. within the capacity of the apparatus, by providing the requisite number of stationary contact elements for successive engagement by the rotating arms of the distributor mechanism and by connecting each plug to corresponding stationary contacts of the'distributor mechanism.

The spark plugs preferably comprise each a suitable support base a formed preferably ior removabl attachment on the engine or device It, with which the plug is associated. The base 8! supports a suitable insulator 4i carrying a pair of sparking terminals 0, both of which are insulated from the base ll so that the entire high voltage system is insulated and is electrically symmetrical with respect to ground. i

The construction as shown exemplifies a balanced two-wire systemwherein the two sides of the circuit are identical and symmetrical with respect to ground. That is to say. the capacities from the various elements in the circuit to ground and the series inductances of the leads are identical on the two sides of the circuit. A radio frequency voltage across the spark gap will set up identical currents of opposite polarity in the two sides. As a consequence of the symmetrical arrangement of the high tension portions of the ignition system, current traveling to a spark plug along one side oi the circuit loop will be exactly matched by current traveling in the opposite direction away from the plug along the other side of the loop. Any high frequency radiation caused by the current traveling one side of the circuit will be balanced and cancelled by a corresponding and opposed radiation caused by the current in the other side of the circuit. The two conductors comprising the cable section Ii and the cable section a are maintained in closely adjacent relationship the one with respect to the other for the purpose of obtaining optimum cancellation-eonditions in each loop circuit, Whe. eby the system encountered. Twisting the conductors together also serves to equalize capacity reactance between each of the conductors and ground, whereby the electrical characteristics of both sides of each spark plug circuit are substantially equalized in order to render the ignition system inherently seli-canceliingwith r pect to interference eiiects created as a result of the operationottbcsystem An incidental advantage of the present bal anced two-wire system is that the insulation thickness can be reduced to about one-half that needed in the conventional system because each of the leads will carry only one-half of the sparking voltage. v

The balanced system of Fig. 1 will be found suitable for automobiles. motorboats, and certain airplane applications where a relatively inexpensive means of minimizing radio interference is desired. Where expense is not the controlling consideration and quality of performance is. the

system of Fig. 2 is to be desired, and will be found suitable for the most critical applications such as in large commercial and military airplanes.

In many applications the balanced two-wire ignition system of the present invention will operate satisfactorily from an interference standpoint without the use of shielding, since the balanced two-wiresystem results in a cancellation of the radiations from the two sides of the circuit. This is particularly the case where the conductors are twisted the one about the other. However, because of slight inequalities in a practical application, this cancellation is not quite complete. .Because of this residual radiation, it will be found desirable to use these shields. It is relatively easy to shield residual radiation resulting from slight unbalance in a balanced two-wire system, as compared with shielding conventional unbalanced ignition systems where there is no inherent cancellation and where the radiation is present to a much greater degree. In a conventional system embodying a continuous shield of low resistance material completely surrounding iihe high tension system and extending from the base of the plug to the source of high tension, all the radio frequency components of the ignition current traveling to the spark plug will be forced to return to the source along connectedconductors connected for the control of the power source. Where shielding is applied, however, the quality of shielding required for maintaining interference within a predetermined degree of minimum interference may be less perfeet than the quality of shielding required in conventional ignition systems for a prescribed minimum degree of radio interference. As a cona sequence. the present invention employs simplifled, less expensive shielding and reduces the maintenance work required to keep the requisite shielding in effective operating condition. The present invention thus serves to eliminate radio interference to a much higher degree. by shielding, than is possible with conventional ignitionsystems.

An ignition system embodying the present invention may comprise one or more two-electrode spark plugs in which both electrodes are insulated from ground. Each of the. plugs is con-- nected to the distributor II by a pair of electrical conductors, comprising the cable section ll. These conductors are both insulated from ground and may be twisted the one about the other, as

shown in Figs. 1 and 2. or may be left untwisted but disposed in closely adjacent relationship, as

" shown in Figs. 4 and 5.

The distributor 2|, as shown in'Figs. l; 2 and 4, may comprise two distributor devices 35 and 31, each embodying an insulated contact arm and a set of cooperating stationary contacts for routing the sparking current delivered from the power source through the distributor arms and successively through the cooperating distributor contacts tothe several spark plugs. The conductors ofthe cable section 3i from each plug are connected with corresponding contacts of the two the inner surface of the shield. Though such shielding is, to some extent, effective, trouble arises in actual practice because it is very. diflicult to maintain a continuous shield of low resistance under service conditions of heat, cold, moisture, dirt. oil. vibration, and corrosion. and with even minor distortionof the shielding serious radio disturbances result.

The utilization of a two-wire balanced system with a shield has important advantages over the use of a shield in a conventional system, in that if a break in shielding should occur, in the latter system a radio frequency voltage will appear across the break resulting in radio interference. Such radio frequency voltage will be very much higher than in the case of the balanced twowire system and the disturbance in radio reception will be correspondingly much larger.

Improved interference suppression, therefore. is obtained by shielding the cable sections 3i and 33, including the spark plugs themselves, as well as the distributor mechanism and the power source i5, whether the same comprises an ignition coil or a magneto, it being also desirable, for optimum results, to shield any switch and interdistributor devices. The contact arms of the distributor devices are connected to the opposite ends of the high tension winding I! by means of the conductors forming the cable section II. The arms, of course. will be rotated in synchronism to engage the corresponding contacts of both devices simultaneously.

As shown more particularly in Fig. 1 of the drawings, the high tension cell i! may comprise the secondary winding of atransformer l5, having an iron core and a primary winding 41, one

side of which is preferably grounded, as at ll.

and connected as by the conductor I, with one side of a source of electrical potential. such as the battery 53. The other side of the battery II may be connected, through a control switch ll and a conductor 51, to the other side of the primary winding 41, a set of breaker points I bein interposed in the conductor ll between said primary winding and the switch. A condenser It may be connected across the breaker points for spark suppression. and a filter condenser 63 may be connected between the conductors II and I! in order to minimize interference originated in the'primary circuit. Instead of employing the condenser it, the entire primary circuit may be shielded, if desired, and shieldin may be applied to the primary circuit in addition .to the condenser ll.

The foregoing ignition coil system, as shown in Fig. 1, may be applied in the arrangement illustrated in Figs. 4 and 5. It would also re place the magneto power source of Fig. 2.

As shown in Figs. 2 and 3 of the drawings. the ignition system may be-powered by a magneto in place of the battery-ignition coil shown in Fig. 1. To this end. the high tension coil II, in Figs. 2 and 3 comprises the secondary winding of a magneto is having a primary winding 05, the opposite ends of which are connected, as bymeans of conductors i1 and 89 across a set of breaker points ll, condenser means 13 being connected in parallel relationship with respect to said breaker points. The magneto is connected with a control switch I by suitable conductor means which, asshown in Fig. 2, may comprise a twowire cable 11 connecting the switch with the conductors El and 59. The conductors of the cable 11 may be twisted the one about the other, as shown, or the conductors may remain untwisted in closely adjacent relationship. As shown in Fig. 2, the winding 65 may be provided with a grounded center tap, or an end of the primary winding 65 may be connected to ground, as shown in Fig. 3, grounding of the coil, in both cases, being accomplished conveniently by making electrical connection with the grounded magneto housing 21, as indicated at 19. In the arrangement shown in Fig. 3, the magneto is connected with one side of the switch 15 by means of a conductor 8| connected to the ungrounded side of the magneto winding 65, the other side of the control switch." being grounded, as shown at 83. The cable means connecting the switch 15 with the magneto system, in each case, may be shielded by means of a tubular metallic shield 05 extending between the switch 15 and the magneto housing 21 in position surrounding the cable, said shield being preferably grounded, as shown.

The magneto system shown in Fig. 2 thus comprises a shielded balanced two-wire primary circuit with the primary coil provided with a grounded center. tap, effective in minimizing radiations from the leads running from the magneto to the ignition switch at the control point. These leads in large airplane installations, are very long and give rise to considerable interference with radio reception. The control switch leads in a conventional system act as an effective antenna to radiate interferences originating in the primary circuit and in some cases the secondary circuit. Where optimum performance is not a criterion but where expense is the primary consideration, the low voltage shielding shown in Fig. 2 may be omitted and the system will operate eifectively in suppressing interference to a substantial degree.

The foregoingmagneto systems, as shown in Figs. 2 and 3, may be applied in the arrangements illustrated in Figs. 4 and 5.

An alternative system for minimizing radio interference, shown in Fig. 5, employs a standard one-arm, four contact distributor mechanism 81 in place of the dual unit distributor shown in Figs. 1, 2 and 4. The system shown in Fig. 5 also embodies a power source comprising high tension coil i5, one side of which may be grounded. The system, if grounded, will of course be unbalanced. The spark plugs, however, each have a pair of insulated sparking electrodes 43 connected each to the distributor by an insulated conductor of the cable Ii, one conductor of the cable section being connected with the appropriate stationary contact of the distributor and the other being connected at a central connection point 89, within the grounded distributor housing 25, at which central point are also connected one side of each of the connected spark plugs and also one side of the coil II. The connection point may be grounded, as shown, or may be insulated from ground. This arrangement is advantageous in that an insulated return path is provided for spark plug current, whereby the current is prevented from seeking multiple ground. paths back to thehigh tension coil, as is the case where one sparking electrode of each plug is nections being accomplished through the conductors of the cable section I3. All of the return leads from the various spark plugs are connected at the central or common point" lying within the distributor casing. i

This arrangement will eliminate circulation of ignition currents anywhere except in the conductors forming the cable section II and It, the

only current circulating other than in said conductors being the small induced current arising as a result of current circulation in the conductors themselves. .Eflective noise elimination is thus obtained. The connection of the high tension coil II at the common point ll also eliminates the establishment of circulating currents other than in the conductors forming the cable sec-. tion 33. I

In the Fig. 5 embodiment, the conductors form. ing the cable sections II and 33 may be twisted the one about the other as heretofore described. or they may remain in untwisted closely adjacent relationship, as shown. For optimum results, the high tension circuits of the ignition system should be shielded. This may be accomplished by forming the housings 2i and 21 as interference shields enclosing the power source and distributor means, and by applying grounded metal tubes ll, comprising sheaths, in position enclosing the cable sections 3| and 33 outwardly of the housings. The sheath enclosing a cable section 3i may be formed with an enlargement 3 at one end to enclose the exposed portions of the spark plug to which the cable section is connected. Likewise, the tubular sheaths may be formed, as at 95, to facilitate mechanical connection thereof with the housings 25 and 21, and to accommodate entry of the cable sections into the housings.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the I several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for .the purpose 0! illustrating the invention. I

The invention is hereby claimed as follows:

1. An ignition system comprising the combination, with a spark plug, having a pair oi'insulsted sparking electrodes, and a source of sparking energy comprising a high tension coil, of circuit means including a pair of insulated conductors for delivering electrical sparking energy to said electrodes from said source, said coil having a grounded center tap to thereby establish balanced circuit conditions in said ignition system whereby each'of said conductors, at any instant,wiil be energized at a potential. with respect to ground, equal and opposite to the potential of the other conductor, and said conductors having substantially identical electrical characteristics and being arranged in side-by-siderelationship between the plug and said source to thereby cancel and suppress interference eitects set up by current 2. An ignition system comprising the combination, with a spark plug having a pair of insulated sparking electrodes, and a source of sparking energy, of circuit means including a pair or canductors for delivering electrical sparking energy to said electrodes from said source, said conductors being arranged in side-by-side relationship between the plug and said source to thereby cancel and suppress interference eilects set up by current flow in opposite directions in said conductors when the system is in operation. the conductors of a said pair of conductors being twisted the one about the other to aid in equalizing their mutual electrical characteristics and the characteristics of each with respect to ground.

3. An ignition system comprising the combination, with a spark plug having a pair of insulated sparking electrodes, a source of sparking energy and distributor means, of circuit means for sup plying sparking power from said source through the distributor means to said plug comprising a pair of insulated electrode connected conductors connecting the electrodes with the distributor means, said distributor means comprising a pair or distributor devices each having a rotary arm and cooperating stationary contacts successively engageable by the arm as the same rotates, means to rotate said arms in unison to simultaneously engage corresponding contacts of said devices, and a housing forming a grounded interference shield enclosing said distributor devices, the arms of said devices being electrically connected with said power source and said electrode connected pair of conductors being electrically connected with corresponding contacts of said distributor.

including an interference shield comprising a grounded sheath enclosing at least one of said pairs of conductors outwardly of said distributor housing. 7

6. An ignition system comprising the combination, with a spark plug having a pair oi insulated sparking electrodes and a source oi sparking energy, of circuit means for delivering electrical sparking; energy to said electrodes from said source, said circuit means including a pair of conductors having substantially identical, electrical characteristics and being arranged in sideby-side relationshipbetween the plug and said" source to thereby. cancel and suppress interference eifects set up by current flow in opposite direc tions in said conductors when the system is in operation, said power source comprising a mag-'- neto having a high tension winding connected with said sparking electrodes through said pair of conductors, a low tension winding connectedv 5 in circuit with a set of breaker points, a grounded shield enclosing saidmagneto, a control switch remote from said magneto, and cable meansconnectingsaid switch in circuit with said magneto I and extending outwardly ofsaid rhield, said cable means comprising a pair of conductors twisted the .one about the other and said low tension winding having a grounded center tap.

7. An ignition system comprising the combination, with a spark plug having a pair of insulated sparking electrodes and a' source of sparking energ'y, of circuit means for delivering electrical sparking energy to said electrodes from said source, said circuit means including a pair of conductors having substantially identical elec-' trical' characteristics and being arranged in sideby-side relationship between the plug and saidsource to thereby cancel and suppress interferonce eflects set up by current flow in opposite directions in said conductors when the system isin operation, said power source comprising a magneto having a high tension winding connected withsaid sparking electrodes through said pairof conductors, a low tension winding connected in circuit with a set of breaker points, a grounded shield enclosing said magneto, a control switch remote from said magneto, cable means connecting said switch in circuit with said magneto and extending outwardly of said shield, and a grounded sheath enclosing said cable means between said shield and switch, one side of said circuit and low tension coil being grounded and said cable means comprising a'conductor connecting one side oi the switch with the ungro'unded or high side oi'said circuit, the other side or said switch being adapted for connection to ground. v

8. An ignition system comprising a high tension spark plug firing circuit including a spark-' ing plug and a source of plug firing power, said circuit extending between the source and the plug to be tired, said circuit comprising a loop circuit embodying matched conductors and having substantially identical electrical characteristic with respect to each other, said conductors forming opposite sides oi said loop circuit whereby interfering disturbance established by cur rent how to the plug along one side of said loop circuit will be cancelled and suppressed by qual and opposite disturbance set up by current flow from the plug along the other side-oi said loop circuit, saidconductors being arranged in closely adjacent juxtaposition substantially throughout the length thereof between the plug and said source, a distributor comprising dual distributor units. said units being connected in said conductors on opposite sides of said loop circuit, said distributor units each comprising an arm electrically connected with said source and adapted for rotation ynchronously with the other arm, and a set or contactsior each arm positioned for successive engagement thereby as the same rotates, whereby corresponding contacts of the units may be engaged simultaneously each by its cooperatingarm, a pair of said cooperating contactsbeing adapted for connection with i the electrodes oi said-plug.

9. An ignition system comprising a high tension spark plug firing circuit including a sparking plug and a source of plug firing power, said circuit extending between the source and the plug to be ,flred,'said circuit comprising a loop circuit embodying matched conductors and hav- 1 ing substantially identical electrical characterisiorming opposite sides of aid loop circuit whereties with respect to each other, said conductors a by interfering disturbance established by current flow to the plug along one side oi said loop circuit will be cancelled and suppressed by equal and opposite disturbance set up-by current flow from the plug along the other side of said loop circuit, said conductors being arranged in closely adjacent juxtaposition substantially throughout the length thereof between the plug and said source, including a distributor comprising a grounded housing, a rotary arm and cooperating stationary contacts within and insulated from said housing. saidarm and one ofsaid contacts being respectively connected with said source and tion, with a spark plug having a pair of insulated sparking electrodes, a source of sparking energy and distributor means. of circuit means for supplying sparking power from said source through the distributor means to said plug comprising a pair of insulated electrode connected conductors connecting the electrodes with the distributor means and having substantially identical reactive characteristics with respect to ground throughout the length thereof between the plug and distributor means, and a pair of insulated source connected conductors connecting .the source to said distributing means having substantially identical reactive characteristics with respectto ground throughout the length thereof between said source and said distributor means. said source comprising a high tension coil having a grounded center tap. said distributor means comprising a pair of distributor devices each comprising a rotary arm and cooperating stationary contacts. said arms being electrically connected with the opposite sides of hold high tension coil through said source connected pair oi conductors, said electrode connected pair of conductors being electrically connected to corresponding contacts of said distributing devices, whereby the ignition system comprises a balanced circuit between the power source and said spark plug in which each conductor of said conductor pairs, at any instant, will be at a potential with respect to ground that is equal and opposite to the potential of the other conductor of the pair. v

11. An ignition system comprising the combination, with a spark plug having a pair of insulated sparking electrodes and a source of sparking energy. of circuit means for delivering electrical sparking energy to said electrodes from said source, said circuit means including a pair of conductors having substantially identical elec-' trical characteristics and being arranged 'in sideby-side relationship between the plug and said source to thereby cancel and suppress interference eflects set up by current iiow in opposite directions in said conductors when the system is in operation, said power source comprising a magneto having a high tension winding connected with said sparking electrodesthrough said pair of conductors, a low tension winding connected in circuit with a set of breaker points. a grounded shield enclosing said magneto, a control switch remote from said magneto,. and cable means concable means connecting said switch in circuit necting said switch in circuit with said magneto and extending outwardly of said shield.

12. An ignition system comprising the com-- bination, with a spark plug and a source oi." sparking energy, of circuit means including a conductor for delivering electrical sparking energy to said spark plug from'said source, said source comprising a ma neto having a high tension winding connected with said spark plug through said connector, a low tension winding connected in circuit with a set or breaker points, a grounded shield enclosing said magneto, a

' I 1 control switch remote from said magneto. and

with said magneto and extending outwardly of said shield, said cable means comprising a pair of conductors having substantially. identical electrical characteristics and being arranged in' side-by-side relationship between the grounded shield and said control switch to thereby cancel and suppress interference eilects set up by cur-' rent flow in opposite directions in said conductors when the system is in operation.

13. An ignition system comprising the combination, with a spark plug and a source of sparking energy and distributor means, of circuit meansincluding a conductor for delivering electrical sparking energy from said source through the distributor means to said spark plug, said source comprising a magneto having a high tension winding connected with said spark plug through said connector, a low tension winding connected in circuit with a set of breaker points, a grounded shield enclosing said magneto, a control switch remote from said magneto, cable means connecting said switch in circuit with said magneto and extending outwardly of said shield, said cable means comprising a pair of conductors twisted the one about the other to aid in equalizing their mutual electrical characteristics and with respect to ground to thereby cancel and suppress interference effects set up by current flow in opposite directions in said conductors when the system conductor for delivering electrical sparking energy to said spark plug from said source, said source comprising a magneto having a high tension winding connected with said spark plug through said connector, a low tension winding connected in circuit with a set 0! breaker points, said low tension winding having a grounded center tap, a grounded shield enclosing said magneto, a control switch remote from said magneto. and cable means connecting said switch in circuit with said magneto and extending outwardly of said shield, said cable means comprisin apair of conductors having substantially identical electrical characteristics and being arranged in side-by-side relationship between the grounded shield and said control switch to thereby cancel and suppress interference elects set up by current how in opposite directions insaid conductor when the system is in operation;

15. An ignition system comprising the combination; with a spark plug, a source of sparking 1.,

energy and distributor means, of circuit means including a conductor for delivering electrical 1.

sparking energy from said source through the distributor means to said spark plug, said source comprising a ma neto having a high tension winding connected with said spark plug through said connector, a lowtension winding connected in circuit with. a set of breaker points, said low a tension winding having a grounded center tsp, a grounded shield enclosing said magneto, a

control switch remote munv said magneto, cable means connecting said switch in circuit with Y said magneto and extending outwardly 0! said shield, said cable means comprising a pair of conductors having substantially identical electrical characteristics and being arranged in 1a side-by-side relationship between the grounded shield and said control switch to thereby cancel and suppress interference effects set up by current flow in opposite directions in said conductor when the system is in operation, and a grounded sheath enclosing said cable means between said shield and switch.

and suppress interference eilects set up by cur-- rent flow in opposite directions in said conductor when the system is in operation, ,one of said conductors connecting one side of the switch 16. An ignition system comprising the combination, with a spark plug and a source of sparking ener y, of circuit means including a conductor for delivering electrical sparking energy to said spark plug from said source, said source comprising a magneto having a high tension winding connected with said spark plug through said connector, a low tension winding connected in circuit with a set of breaker points agrounded shield enclosing said magneto, a control switch remote from said magneto, cable Qmeans connecting said switch in circuit with said magneto and extending outwardly of said shield, one side of said circuit and low tension coil being grounded, said cable means comprising a pair of conductors having substantially identical electrical characteristics and being arranged in side-by-side relationship between the grounded shield and] said control switch to thereby cancel with the ungrounded or high side ot said circult, and'a grounded sheath enclosing said cable means between said shield and switch.

VICTOR WELGE.

nnmanncns crran The following references are of record in the file of this patent:

UNITED STATES PATENTS France 1929 

